1. Field of the Invention
The present invention relates to an image-forming apparatus, such as a digital copier, for forming images of documents on sheets of paper, and more particularly to a maintenance system for adjusting the operation state of an image-forming apparatus with the aid of an external apparatus.
2. Description of the Related Art
There are a plurality of variables to be set for image-forming apparatuses such as digital copiers which affect the state of the images formed, such as drive voltages of light sources and I/O conversion curves when the images are processed. In addition, the optimum values of such variables to be set vary depending on the progress of fatigue of the apparatuses and the types of documents. Accordingly, in order to maintain the proper state of the images formed by image-forming apparatuses at all times, the values of the plurality of variables must be adjusted for optimization at relatively short intervals.
It is difficult and complicated, however, for the user to properly adjust the plurality of variables, and therefore a maintenance system has been eagerly sought which facilitates the adjustment of the values of the respective settings.
A solution is presented in Japanese Examined Patent Application HEI 6-44791 which discloses a remote trouble-shooting method for communication terminals, wherein the center requests the communication terminal to send the set operational parameters to verify and modify the settings of the operational parameters, and instructs the communication terminal to reset the operational parameters based on the modified settings.
In addition, Japanese Examined Patent Application HEI 6-95240 discloses an image-forming apparatus by which a given test chart is output as an image which is in turn read as a document, and the features are precisely adjusted on the basis of the image data of the read test chart while preventing interference between the spatial frequencies of the image-reading device and the spatial frequencies of the image-output device.
Being designed to modify the settings for the operation state according to preset operational parameters or on the basis of the results of reading of a predetermined test chart, however, the image-forming apparatuses of the prior art have the problem of being incapable of accomplishing high-precision adjustment when the document is not of an expected type, for example. An additional problem is that since the image-forming operation must be suspended until the adjusting operation is completed, and thus the image-forming operation cannot be completed rapidly.